Nowadays, various software data including audio data such as music, picture data such as movies, game programs, various application programs (hereinafter called “content”) are circulating via a network such as the Internet or via an information recording medium (media) such as a CD (Compact Disc), a DVD (Digital Versatile Disc), an MD (Mini Disk). Such circulating content is played and used in a playback apparatus such as a PC (Personal Computer), a CD player, a DVD player, an MD player, a game machine, or the like owned by a user.
As to many of content such as music data, movie data, their distribution rights and the like are usually held by their creators or sellers. Therefore, when such content is distributed, it is commonplace to impose certain limitations on its use; i.e., to license use of the content to only an authorized user to prevent unauthorized duplication and the like.
Particularly in recent years, recording apparatuses and storage media that digitally record information are becoming popular. Using these digital recording apparatuses and storage media, recording, playback can be repeated without deteriorating, images and sound, for example. Since digital data can be copied again and again with their image and sound quality maintained, once illegally copied storage media come to circulate through the market, the interests of the copyright holders, legitimate distributors and the like of various content such as music, movies would be damaged. In order to prevent such unauthorized copying of digital data, various processing configurations have been implemented or proposed nowadays for preventing illegal copying to digital recording apparatuses and storage media.
Devised as some copyright protection technologies to prevent such situations is an information recording medium provided with a copy control function (e.g., a CD with a copy protection function). The copy protection function includes, e.g., copy control technology developed by Midbar Tech Ltd. and copy control technology developed by Macrovision Corporation, U.S.
In these technologies, e.g., a false signal is inserted into the first track of a CD, whereby when the CD is set into a CD-ROM drive of a PC, the PC is not allowed to recognize the CD as a music CD thereby to prohibit playback processing by a CD player program of the PC. An ordinary CD player unable to perform ripping processing can execute playback of only the content data by neglecting the false signal.
When trying to play an information recording medium such as a CD having copy-controlled content recorded thereon, a playback-only CD player can play the content, but a PC or the like cannot play it.
However, such copy-protected processing might end up in hampering use of content in which, e.g., one enjoy playing the content in a portable player or the like by copying or moving the content to a PC, and then by, e.g., copying it to a recording medium such as a flash memory.
As an approach to accommodating situations such as above, a configuration has been proposed, wherein content to be stored on an information recording medium such as a CD is distributed after encryption, and also a license is provided to a user, in which content usage right information including a limitation on the number of copies of the content, a limitation on the period of use of the content is described. This configuration allows use of the content in various forms, such as permitting only a user having purchased the license to acquire a key for decrypting the encrypted content to perform copying and the like of the content under predetermined limitations whereby to implement copyright protection for the content and improve user convenience.
For example, SDMI (Secure Digital Music Initiative) that has proposed various music distribution technology specifications proposes standards of copyright protection functions for portable players. Implementations of copyright protection functions come in various forms, such as a limitation on the number of copies of content, a limitation on the period of use of the content. Thus, by purchasing a license wherein usage right information corresponding to the content is set, the user can use the content under predetermined conditions.
The encrypted content and its license are distributed independently. A typical, conventionally proposed configuration therefor is to provide the encrypted content to a user after storage on an information recording medium such as a CD, a DVD, an MD, and to distribute the license via, e.g., a network such as the Internet. For example, a user who has purchased a CD having encrypted content stored thereon establishes a connection to a license provider using a network-connectable terminal such as a PC, performs a license acquiring process that is conditional on payment of a predetermined fee, further acquires a key applied to decryption of the encrypted content on the basis of the acquired license, and thereafter decrypts the encrypted content using the acquired key for playback.